Many thanks 'just a guy', that was exactly the sort of feedback I was seeking. I feel even more comfortable leaving things as they are after reading your very eloquent and enlightening post.
I will let Leo Beranek have the final say on the matter - the following two quotes are taken from his classic 1954 "Acoustics" book:
"A frequency-response curve of a loudspeaker is defined as the variation in sound pressure or acoustic power as a function of frequency, with some quantity such as voltage or electrical power held constant."
"Whether one considers sound pressure or power radiated, the frequency-response curve when expressed in decibels has the same shape, provided the directivity factor is constant."
Now you make me wonder what you missed in school?
Nevile Thiel was Australian.
Richard Small an American
Floyd Tools a Canadian.
Seems to me that with but a few examples it can be shown that no one country has cornered the market on intelligence.
The noise power in this thread has been fairly high lately - regardless if it has been expressed in dB re 1pW or as equivalent SPL at 1m
.Sock-Puppet ...
... on Steroids or maybe
Jabba the Hutt
WHG
As in 'Yabba the Mutt'?
... on Steroids or maybe
Jabba the Hutt
WHG
Attachments
I would be very interested to see the data proving that to be the case.
I have no problems with you continuing to believe that Hornresp plots guns and roses. I think however that it is probably time to call a halt to this discussion - it must be boring everyone else to distraction by now. Accordingly, I will not be responding to any more posts from anyone on the choice of the title "Acoustical Power" to describe the chart in Hornresp which plots the ratio in decibels of output sound power to a fixed reference sound power.
To allow you to move on, it may be better if you just delete Hornresp from your computer and try to forget you ever saw it. There are much more important things in life to worry about than a silly loudspeaker simulation program.
Hi Bill,
It took me ages to find a photo of the canine equivalent to Jabba. "Mutt" was the only respectable object I could think of. A picture of "Yabba the Butt" doesn't bear thinking about
.Kind regards,
David
Further to the above, it is not necessary to first calculate W if only the PWL referenced to 1 picowatt is required. The relevant expression becomes:
PWL = SPL + Offset
Where:
Offset = 10 * Log10(Ang / 1.0363)
If Ang = 4 * Pi then Offset = 10.84 dB
If Ang = 2 * Pi then Offset = 7.83 dB
If Ang = 1 * Pi then Offset = 4.82 dB
If Ang = 0.5 * Pi then Offset = 1.81 dB
It is close enough just to remember that the 4 Pi offset is 10.8 dB, and that the offset value reduces by 3 dB each time that the solid radiation angle is halved.
An example for the English-speaking realms thou have given. In the schoolbooks i read about (electro)acoustics, Leistung (power) wird (becomes) nicht (not) bezogen (referenced) auf (to) einen (a) Abstrahlwinkel (radiation angle).David said:
Wrong! Power is the integral of sound pressure over a full detection sphere. PWL is that power referenced to another power of usually 1 pW.
True for a driver much smaller than wavelength! But Hornresp does not use that formula of thee. At such a low acoustic frequency, if Ang is halved in Hornresp, then "power" rises by 6dB, while it should do so by 3dB only.
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